WO2015064430A1

WO2015064430A1 - Laminate body, insulating cooling plate, power module, and production method for laminate body

Info

Publication number: WO2015064430A1
Application number: PCT/JP2014/078003
Authority: WO
Inventors: 優赤林; 雄一郎山内; 慎二斎藤; 真也宮地
Original assignee: 日本発條株式会社
Priority date: 2013-10-28
Filing date: 2014-10-21
Publication date: 2015-05-07
Also published as: JP2015086085A; JP6096094B2

Abstract

Provided is a laminate body wherein the adhesive strength between a ceramic and a metal coating is high, and wherein breaks in a ceramic substrate that result from a difference in the thermal expansion of the ceramic substrate and the metal coating during a heat cycle can be prevented. Also provided are an insulating cooling plate, a power module, and a production method for the laminate body. In the present invention, an electronic circuit board (1) is provided with: an insulating ceramic base material (10); an intermediate layer that has as a principle component a metal or an alloy that is formed on the surface of the ceramic base material (10); a first metal circuit layer (21) that has a porosity of 5%-15% and that is formed by accelerating a metal-containing powder and a gas toward the surface of the intermediate layer and spraying and depositing the powder onto said surface in a solid-phase state; and a second metal circuit layer (22) that has a porosity of 0%-0.5% and that is formed by accelerating a gas and a powder that contains the same metal as forms the first metal circuit layer (21) toward the surface of the first metal circuit layer (21) and spraying and depositing the powder onto said surface in a solid-phase state.

Description

Laminated body, insulating cooling plate, power module, and manufacturing method of laminated body

The present invention relates to a laminate, an insulating cooling plate, a power module, and a method for producing the laminate.

Conventionally, power modules have been known as energy-saving key devices used in a wide range of fields from power control to motor control for industrial and automotive applications. The power module has a heat radiating plate that radiates heat from the semiconductor chip through an insulating substrate as a base material. The heat radiating plate is made of a metal or a ceramic composite, and has a moving path for a cooling heat medium. The heat radiating plate is connected to the surface of a ceramic base material, which is an insulating substrate, by a brazing material or the like. In recent years, a cooling plate that uses heat radiation of ceramics to dissipate heat has been developed, and heat generated from semiconductor chips (transistors) stacked on the surface of the ceramic substrate where the flow path is not formed. Can be emitted from the cooling plate to the outside, thereby cooling the electronic circuit board such as the power module. A circuit pattern made of a metal film is formed between the ceramic substrate and the semiconductor chip.

By the way, in an electronic circuit board such as a power module described above, an intermediate layer mainly composed of a metal or an alloy is formed on the surface of a ceramic substrate, and then a metal film such as a circuit layer or a cooling plate is formed by a cold spray method. The technique to do is proposed by the present applicant (see, for example, Patent Documents 1 and 2). In Patent Documents 1 and 2, although a metal film with high adhesion can be formed by forming a metal film on the ceramic substrate via an intermediate layer, the adhesion between the ceramic substrate and the metal film having a large thermal expansion difference. Therefore, the substrate such as alumina, which is inferior in heat resistance, may be cracked due to thermal stress under a thermal cycle.

In addition, a method of manufacturing a heat transfer member having a two-layer structure including a lower layer film having a porous structure and an upper layer film having a porous structure having a structure different from that of the lower layer film has been proposed (for example, Patent Document 3). reference). In Patent Document 3, the difference in thermal expansion between the insulating member and the heat sink can be reduced by forming the lower layer film and the upper layer film by the cold spray method while changing the density with the same material. However, since Patent Document 3 is not a technique for directly forming a metal film on a ceramic substrate, it cannot be used for manufacturing a cooling plate made of a ceramic substrate.

Japanese Patent No. 5191527 JP 2013-018190 A JP 2009-127086 A

The present invention has been made in view of the above, and in the case of producing a laminate in which a metal film is formed on a ceramic substrate using a cold spray method, the adhesion strength between the ceramic and the metal film is high. To provide a laminate that is high and can prevent cracking of the ceramic substrate due to a difference in thermal expansion between the ceramic substrate and the metal film under a thermal cycle, and an insulating cooling plate, a power module, and a method for producing the laminate Objective.

In order to solve the above-described problems and achieve the object, the laminate according to the present invention includes an insulating ceramic base material and an intermediate layer mainly composed of a metal or an alloy formed on the surface of the ceramic base material. And a first metal having a porosity of 5 to 15% formed by accelerating a powder containing a metal together with a gas on the surface of the intermediate layer and spraying and depositing the powder in a solid state on the surface. By accelerating a powder containing the same metal as the metal forming the first metal film on the surface of the film and the first metal film together with the gas, and spraying and depositing the powder in the solid state on the surface And a formed second metal film having a porosity of 0 to 0.5%.

In the laminate according to the present invention, in the above invention, the intermediate layer is composed of a metal or an alloy as a main component, the first intermediate layer forming a layer on the first metal film side, an active metal, or an active metal. A second intermediate layer made of an oxide or a hydride and in contact with the first intermediate layer and laminated by being bonded to the ceramic substrate on a surface different from the surface in contact with the first intermediate layer. The first intermediate layer and the second intermediate layer are formed by applying a brazing material to the ceramic base material and then performing a heat treatment.

The laminate according to the present invention is characterized in that, in the above invention, the intermediate layer is formed by heat treatment in a vacuum.

In the laminate according to the present invention, in the above invention, the second intermediate layer includes at least one selected from the group consisting of any metal of titanium, zirconium, hafnium, germanium, or a metal hydride. It is characterized by that.

The laminate according to the present invention is characterized in that, in the above invention, the first intermediate layer includes at least one selected from the group consisting of gold, silver, copper, aluminum, and nickel.

The laminate according to the present invention is characterized in that, in the above invention, the intermediate layer is formed by heat treatment in the atmosphere.

In the laminate according to the present invention, in the above invention, the second intermediate layer is made of titanium, zirconium, hafnium, germanium, boron, silicon, aluminum, chromium, indium, or a metal oxide or hydride. It includes at least one type selected.

The laminate according to the present invention is characterized in that, in the above invention, the first intermediate layer contains at least one of gold and silver.

The laminate according to the present invention is characterized in that, in the above invention, the first metal film and the second metal film are made of copper, aluminum, or an alloy of these metals.

The laminate according to the present invention is characterized in that, in the above invention, the ceramic substrate is alumina.

Moreover, the insulating cooling plate of the present invention is an insulating cooling plate comprising the laminate according to any one of the above, wherein the ceramic base material has a heat radiating portion, and the first metal film and the The second metal film is a circuit layer.

Moreover, the power module of this invention is a power module which has a laminated body as described in any one of the above, Comprising: The said ceramic base material is an insulated substrate, The said 1st metal film and the said 2nd metal film are It is a circuit layer, The cooling plate which has copper or aluminum as a main component is formed in the surface different from the surface in which the said 1st metal film and the said 2nd metal film of the said insulated substrate were formed.

The method for producing a laminate of the present invention is a method for producing a laminate in which a metal film is formed on the surface of a ceramic substrate, and an intermediate comprising a metal or an alloy as a main component on the surface of the ceramic substrate. An intermediate layer forming step for forming a layer and a surface of the first intermediate layer formed by the intermediate layer forming step are accelerated with a gas containing a metal together with a gas and sprayed on the surface in a solid state. A first metal film forming step for forming a first metal film having a porosity of 5 to 15% by deposition; and the same metal as the metal for forming the first metal film on the surface of the first metal film A second metal film forming step of forming a second metal film having a porosity of 0 to 0.5% by accelerating a powder containing gas together with a gas and spraying and depositing the powder on the surface in a solid state. ,including And wherein the door.

Moreover, the manufacturing method of the laminated body concerning this invention is the said invention WHEREIN: The said intermediate | middle layer formation step WHEREIN: The brazing material arrangement | positioning step which arrange | positions a brazing material with respect to the surface of the said ceramic base material, and the said brazing material arrangement | positioning By heat-treating the ceramic substrate on which the brazing material is disposed in the step, the ceramic base material is in contact with the first intermediate layer and the first intermediate layer, and on a surface different from the surface in contact with the first intermediate layer. A heat treatment step of forming an intermediate layer having a second intermediate layer bonded and laminated with the ceramic substrate.

The laminated body, the insulating cooling plate, the power module, and the laminated body manufacturing method according to the present invention include: forming a first metal film having a large porosity on the ceramic substrate side by a cold spray method; By forming the second metal film having a low porosity on the first metal film, the first metal film functions as a buffer layer that relieves the difference in thermal expansion from the ceramic substrate, and heat is dissipated by the high thermal conductivity of the second metal film. The effect is excellent.

FIG. 1 is a schematic diagram showing a configuration of an electronic circuit board using an insulating cooling plate that is a laminate according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a configuration of a main part of the insulating cooling plate shown in FIG. FIG. 3 is a cross-sectional view schematically illustrating the formation of the intermediate layer of the insulating cooling plate according to the first embodiment of the present invention. FIG. 4 is a schematic diagram showing an outline of the cold spray apparatus. FIG. 5 is a schematic diagram illustrating a configuration of a power module including the laminate according to the second embodiment of the present invention. 6 is a cross-sectional view showing a configuration of a main part of the power module shown in FIG. FIG. 7 is an electrophotography showing a cross section of the laminate according to Example 1 of the present invention. FIG. 8 is an electrophotography showing a cross section of the laminate according to Comparative Example 3.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment. The drawings referred to in the following description only schematically show the shape, size, and positional relationship so that the contents of the present invention can be understood. That is, the present invention is not limited only to the shape, size, and positional relationship illustrated in each drawing.

(Embodiment 1)
The laminated body concerning Embodiment 1 of this invention is demonstrated in detail with reference to drawings. FIG. 1 is a schematic diagram illustrating a configuration of an electronic circuit board using an insulating cooling plate that is a laminate according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a configuration of a main part of the insulating cooling plate shown in FIG.

The electronic circuit board 1 is an insulating substrate and has a ceramic base material 10 that functions as a cooling plate, a metal circuit layer 20 laminated on the ceramic base material 10, and a metal circuit layer 20 laminated on the electronic circuit board 1 and fixed by solder C1. Semiconductor chip 30.

The ceramic substrate 10 is made of an insulating member, and has a heat radiating portion in which a flow path for a heat radiating fluid is formed on the surface opposite to the surface on which the semiconductor chip 30 is mounted. In the first embodiment, as the ceramic substrate 10, alumina having excellent heat dissipation and aluminum nitride having high thermal conductivity are used in order to function as a cooling plate. However, the ceramic substrate 10 is not limited to this. Since the laminated body according to the first embodiment can relieve thermal stress under a thermal cycle by the metal circuit layer 20 described later, even when alumina having poor thermal shock resistance is used as the material of the ceramic substrate 10, Cracking due to stress can be prevented.

The metal circuit layer 20 includes a first metal circuit layer 21 that is a first metal film laminated on the ceramic substrate 10 and a second metal circuit layer that is a second metal film laminated on the first metal circuit layer 21. 22. The first metal circuit layer 21 and the second metal circuit layer 22 are metal film layers formed by a cold spray method to be described later, and are made of, for example, a metal or alloy having good electrical conductivity such as copper or aluminum. The first metal circuit layer 21 and the second metal circuit layer 22 are formed with circuit patterns for transmitting electrical signals to the semiconductor chip 30 and the like.

The semiconductor chip 30 is realized by a semiconductor element such as a diode, a transistor, or an IGBT (insulated gate bipolar transistor). A plurality of semiconductor chips 30 may be provided on the ceramic substrate 10 in accordance with the purpose of use.

An intermediate layer 50 as shown in FIG. 2 is formed between the ceramic substrate 10 and the first metal circuit layer 21. The intermediate layer 50 includes a first intermediate layer 51 formed on the first metal circuit layer 21 side, and a second intermediate layer 52 formed on the ceramic substrate 10 side.

The first intermediate layer 51 is formed of any one of aluminum, nickel, copper, silver, and gold. The first intermediate layer 51 forms a metal bond with the metal or alloy that is the material of the first metal circuit layer 21 on a surface different from the contact surface with the second intermediate layer 52.

The second intermediate layer 52 is formed of titanium, zirconium, hafnium, germanium, boron, silicon, aluminum, chromium, indium, vanadium, molybdenum, tungsten, manganese, or an oxide or hydride thereof. The second intermediate layer 52 forms a covalent bond with the material of the ceramic substrate 10 on a surface different from the contact surface with the first intermediate layer 51.

Subsequently, formation of the intermediate layer 50 of the electronic circuit board 1 will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view schematically showing the formation of the intermediate layer in the electronic circuit board 1. FIG. 4 is a schematic diagram showing an outline of a cold spray apparatus used for forming a metal circuit layer.

First, as shown in FIG. 3A, a brazing material 50a used as the intermediate layer 50 is applied to one surface of the ceramic substrate 10 by a screen printing method. Here, the brazing material 50a includes a metal or alloy used as the first intermediate layer, and a metal used as the second intermediate layer, or an oxide, hydride, or the like of the metal, and an organic solvent and an organic binder are mixed. Make a paste. As the organic solvent, methyl cellosolve, ethyl cellosolve, isophorone, toluene, ethyl acetate, terpineol, diethylene glycol monobutyl ether, texanol, etc. can be used, and as the organic binder, acrylic resin such as polyisobutyl methacrylate, ethyl cellulose, High molecular compounds such as methylcellulose can be used. The mixing ratio of the organic solvent and the organic binder is preferably 3 to 20% by mass, and preferably 5 to 15% by mass.

After applying the brazing material 50a, heat treatment is performed in a vacuum of 800 to 1000 ° C. or in the air for 1 hour. After the heat treatment for 1 hour, the brazing material 50a becomes the intermediate layer 50 in a state separated into the first intermediate layer 51 and the second intermediate layer 52, as shown in FIG.

Here, when the heat treatment is performed in a vacuum, the first intermediate layer 51 is formed of at least one material selected from gold, silver, copper, aluminum, or nickel, and the second intermediate layer 52 is formed of titanium, zirconium, It is formed from at least one material selected from hafnium, germanium, or hydrides of these metals.

When heat treatment is performed in the atmosphere, the first intermediate layer 51 is made of at least one material selected from gold or silver, and the second intermediate layer 52 is made of titanium, zirconium, hafnium, germanium, boron, silicon, It is formed from at least one material selected from aluminum, chromium, indium, vanadium, molybdenum, tungsten, or manganese, or an oxide or hydride of these metals. The second intermediate layer 52 forms an active ingredient layer. In the case where the intermediate layer is formed by heat treatment in vacuum or in the air, the brazing material 50a for forming the first intermediate layer 51 and the second intermediate layer 52 made of the above-mentioned materials corresponding to the heat treatment in vacuum or in the air. May be used as appropriate.

In addition, the 1st intermediate | middle layer 51 formed by heat-processing in air | atmosphere is applicable as a material of the 1st intermediate | middle layer 51, if it is a metal which does not oxidize even if it melt | dissolves in air | atmosphere. In addition, the second intermediate layer 52 formed by heat treatment in the atmosphere can also use nitrides, carbonides, and hydrides of silicon, calcium, titanium, and zirconium. Any combination of the first intermediate layer 51 and the second intermediate layer 52 described above is applicable. The first intermediate layer and the second intermediate layer include at least one of the listed metals or metal oxides or hydrides. It is also possible to use an alloy mainly composed of any of the listed metals.

The brazing material 50a is heat-treated to form the intermediate layer 50 separated into the first intermediate layer 51 and the second intermediate layer 52, and the first intermediate layer 51 is exposed with the first intermediate layer 51 exposed to the outside. The first metal circuit layer 21 and the second metal circuit layer 22 are formed on the side surface using a cold spray method. Film formation by the cold spray method is performed by a cold spray apparatus 60 shown in FIG.

The cold spray device 60 contains a gas heater 61 that heats the compressed gas, a powder supply device 62 that contains a powder material to be sprayed on the sprayed material, and supplies the powder material to the spray gun 64, and a compressed gas heated by the spray gun 64. And a gas nozzle 63 for injecting the mixed material powder onto the substrate.

As the compressed gas, helium, nitrogen, air or the like is used. The supplied compressed gas is supplied to the gas heater 61 and the powder supply device 62 by

valves

65 and 66, respectively. The compressed gas supplied to the gas heater 61 is heated to, for example, 50 to 1000 ° C. and then supplied to the spray gun 64. More preferably, the compressed gas is heated so that the upper limit temperature of the metal material powder sprayed onto the second intermediate layer 52 and the first intermediate layer 51 laminated on the ceramic substrate 10 is kept below the melting point of the metal material. . This is because the oxidation of the metal material can be suppressed by keeping the heating temperature of the powder material below the melting point of the metal material.

The compressed gas supplied to the powder supply device 62 supplies, for example, material powder having a particle size of about 10 to 100 μm in the powder supply device 62 to the spray gun 64 so as to have a predetermined discharge amount. As the material powder, any one produced by a mechanical process such as an atomizing method or a pulverizing method, or various chemical processes can be used. The heated compressed gas is made a supersonic flow (about 340 m / s or more) by a gas nozzle 63 having a tapered and wide shape. The powder material supplied to the spray gun 64 is accelerated by the injection of the compressed gas into the supersonic flow, and collides with the substrate at a high speed in the solid state to form a film. Note that the apparatus is not limited to the cold spray apparatus 60 in FIG. 4 as long as the apparatus can form a film by colliding the material powder with the base material in a solid state.

The porosity of the first metal circuit layer 21 laminated on the first intermediate layer 51 is 5 to 15%. The porosity of the first metal circuit layer 21 is obtained by performing image processing for dualizing the cross section of the first metal circuit layer 21 with black pores and white metal portions of the first metal circuit layer 21. Calculation was performed based on the ratio of pores to the first metal circuit layer 21. The first metal circuit layer 21 having a porosity of 5 to 15% can be formed by adjusting the temperature and pressure of the compressed gas when forming the first metal circuit layer 21 by a cold spray method. The temperature of the compressed gas when laminating the first metal circuit layer 21 is, for example, 200 ° C. to 600 ° C. when the first metal circuit layer 21 and the second metal circuit layer 22 are formed of copper powder. 300 to 500 ° C is particularly preferable. Further, the pressure of the compressed gas when laminating the first metal circuit layer 21 is, for example, 1.5 MPa to 2.5 MPa when the first metal circuit layer 21 and the second metal circuit layer 22 are formed of copper powder. It is preferable that By setting the temperature and pressure of the compressed gas within the above ranges, the porosity can be 5 to 15%, and the first metal circuit layer 21 is formed between the ceramic substrate 10 and the second metal circuit layer 22. The difference in thermal expansion can be buffered.

The porosity of the second metal circuit layer 22 laminated on the first metal circuit layer 21 is 0 to 0.5%. The porosity of the second metal circuit layer 22 is particularly preferably 0 to 0.1%. Similar to the first metal circuit layer 21, the porosity of the second metal circuit layer 22 may be calculated by the ratio of the area of the pores in the electrophotographic cross section of the second metal circuit layer 22. The second metal circuit layer 22 having a porosity of 0 to 0.5% can be formed by adjusting the temperature and pressure of the compressed gas when forming the second metal circuit layer 22 by a cold spray method. . The temperature of the compressed gas when laminating the second metal circuit layer 22 is, for example, 600 ° C. to 1000 ° C. when the first metal circuit layer 21 and the second metal circuit layer 22 are formed of copper powder. 700 ° C. to 900 ° C. is particularly preferable. Further, the pressure of the compressed gas when the second metal circuit layer 22 is laminated is, for example, 2.5 MPa to 3.5 MPa when the first metal circuit layer 21 and the second metal circuit layer 22 are formed of copper powder. It is preferable that By setting the temperature and pressure of the compressed gas within the above ranges, the porosity can be reduced to 0 to 0.5%, and the second metal circuit layer 22 exhibits the same thermal conductivity as that of the bulk metal and dissipates heat. Can be improved. In addition, since the second metal circuit layer 22 has a dense surface with almost no pores, it has good solder wettability and can prevent poor connection of the semiconductor chip 30.

The arithmetic average roughness (Ra) of the surface of the second metal circuit layer 22 is preferably 10 μm or less. This is because the solder wettability is improved by being 10 μm or less. The arithmetic average roughness (Ra) of the surface of the second metal circuit layer 22 is more preferably 5 μm or less, and particularly preferably 1 μm or less. In order to set the arithmetic average roughness (Ra) of the surface of the second metal circuit layer 22 to 1 μm or less, the second metal circuit layer 22 may be cut after being laminated by the cold spray method. In the present embodiment, if the arithmetic mean roughness (Ra) of the surface of the second metal circuit layer 22 is 10 μm or less, the semiconductor chip 30 can be mounted by soldering, but the surface of the second metal circuit layer 22 is By cutting the arithmetic average roughness (Ra) to 1 μm or less, the occurrence of poor connection of the semiconductor chip 30 can be further reduced. Further, since the oxide layer of the second metal circuit layer 22 can be removed by cutting the surface, it is possible to prevent an increase in electrical resistance and a decrease in thermal conductivity.

In the electronic circuit board 1 according to the first embodiment, the first metal circuit layer 21 and the second metal circuit layer 22 as shown in FIGS. Although the brazing material 50a used in the first embodiment has been described as a paste in which an organic solvent and an organic binder are mixed, the metal or alloy forming the first intermediate layer 51, and the second intermediate layer As long as it contains the metal or metal oxide forming 52, hydride, or the like, it may be in the form of a foil.

According to the first embodiment described above, the adhesiveness between the ceramic substrate and the metal circuit layer is improved, and the thermal stress generated due to the difference in thermal expansion coefficient between the ceramic substrate and the metal circuit layer is increased at a predetermined rate. Since the first metal circuit layer having pores can be relaxed, cracking of the ceramic substrate can be prevented even under a thermal cycle. Moreover, in Embodiment 1, since the roughness of the surface of the 2nd metal circuit layer which mounts a semiconductor chip is small, there exists an effect that solder wettability is good and generation | occurrence | production of a mounting defect etc. can also be suppressed.

(Embodiment 2)
The laminated body concerning Embodiment 2 of this invention is demonstrated in detail with reference to drawings. FIG. 5 is a schematic diagram illustrating a configuration of a power module including the laminate according to the second embodiment of the present invention. 6 is a cross-sectional view showing a configuration of a main part of the power module shown in FIG.

A power module 100 shown in FIG. 5 includes a ceramic substrate 110 that is an insulating substrate, a metal circuit layer 120 formed on one surface of the ceramic substrate 110, and a semiconductor bonded to the metal circuit layer 120 by solder C2. The chip 130 and the cooling fin 140 provided on the surface of the ceramic base 110 opposite to the metal circuit layer 120 are provided.

In the second embodiment, the ceramic substrate 110 is a substantially plate-shaped member made of an insulating material. For example, nitride ceramics such as aluminum nitride and silicon nitride, alumina, magnesia, zirconia, steatite, Oxide ceramics such as forsterite, mullite, titania, silica, and sialon are used.

The metal circuit layer 120 is a metal film layer formed by a cold spray method, and is laminated on the first metal circuit layer 121 and the first metal circuit layer 121 that is the first metal film laminated on the ceramic substrate 110. And a second metal circuit layer 122 that is a second metal film. The first metal circuit layer 121 and the second metal circuit layer 122 are made of a metal or alloy having good electrical conductivity such as copper, for example, and the first metal circuit layer 121 and the second metal circuit layer 122 are formed of the semiconductor chip 130. A circuit pattern for transmitting an electric signal to, etc. is formed.

The semiconductor chip 130 is realized by a semiconductor element such as a diode, a transistor, or an IGBT (insulated gate bipolar transistor), as in the first embodiment. A plurality of semiconductor chips 130 may be provided on the ceramic substrate 110 in accordance with the purpose of use.

The cooling fin 140 is a metal film layer formed by a cold spray method, and includes a first metal film 141 laminated on the ceramic substrate 110, a second metal film 142 laminated on the first metal film 141, Is provided. The first metal film 141 and the second metal film 142 are made of a metal or alloy having good thermal conductivity such as copper, copper alloy, aluminum, aluminum alloy, silver, silver alloy or the like. Heat generated from the semiconductor chip 130 is released to the outside through the ceramic substrate 110 through the cooling fins 140 formed of the first metal film 141 and the second metal film 142.

As shown in FIG. 6, an intermediate layer 150 mainly composed of a metal or an alloy is provided between the ceramic substrate 110 and the first metal circuit layer 121 and between the ceramic substrate 110 and the first metal film 141. Is provided. The intermediate layer 150 includes a first intermediate layer 151 formed on the first metal circuit layer 121 and the first metal film 141 side, and a second intermediate layer 152 formed on the ceramic substrate 110 side. The first intermediate layer 151 and the second intermediate layer 152 have the same configuration as the first intermediate layer 51 and the second intermediate layer 52 of the first embodiment, and a screen printing method is applied to the surface of the ceramic substrate 110. The brazing material used as the intermediate layer 150 is applied by heat treatment in a vacuum at 800 to 1000 ° C. or in the air for 1 hour.

Alternatively, the intermediate layer 150 may be formed by brazing a plate-like metal or alloy member to the ceramic substrate 110 with a brazing material, as in the first embodiment. The intermediate layer 150 is formed, for example, by placing an aluminum (Al) foil on the surface of the ceramic substrate 110 via an aluminum (Al) brazing material and then heat-treating it in a vacuum or in an inert gas atmosphere at a predetermined temperature. It may be what was done.

After forming the intermediate layer 150, the first intermediate layer 151 (if the intermediate layer 150 is a plate-like metal or alloy member brazed to the ceramic substrate 110 with a brazing material) by a cold spray method, First metal circuit layer 121 and first metal film layer 141 (metal circuit layer 120 and cooling fin 140) are formed.

The first metal circuit layer 121 and the second metal circuit layer 122 have the same porosity as the first metal circuit layer 21 and the second metal circuit layer 22 of the first embodiment, respectively. The first metal circuit layer 21 and the second metal circuit layer 22 are laminated at the same compressed gas temperature and pressure.

Also, the arithmetic average roughness (Ra) of the surface of the second metal circuit layer 122 is preferably 10 μm or less, like the second metal circuit layer 22 of the first embodiment. This is because the solder wettability is improved by being 10 μm or less. The arithmetic average roughness (Ra) of the surface of the second metal circuit layer 122 is more preferably 5 μm or less, and particularly preferably 1 μm or less.

The porosity of the first metal film 141 laminated on the first intermediate layer 151 is 5 to 15%. The porosity of the first metal film 141 is calculated by the ratio of the area of the pores in the electrophotographic cross section of the first metal film 141. The first metal film 141 having a porosity of 5 to 15% can be formed by adjusting the temperature and pressure of the compressed gas when forming the first metal film 141 by a cold spray method within a predetermined range. . The temperature of the compressed gas when laminating the first metal film 141 is preferably 200 ° C. to 600 ° C. when the first metal film 141 and the second metal film 142 are formed of copper powder, for example, 300 C. to 500.degree. C. is particularly preferred. The pressure of the compressed gas when laminating the first metal film 141 is, for example, 1.5 MPa to 2.5 MPa when the first metal film 141 and the second metal film 142 are formed of copper powder. Is preferred. By setting the temperature and pressure of the compressed gas within the above ranges, the porosity can be made 5 to 15%, and the first metal film 141 has a thermal expansion between the ceramic substrate 110 and the second metal film 142. The difference can be buffered.

The porosity of the second metal film 142 laminated on the first metal film 141 is 0 to 0.5%. The porosity of the second metal film 142 is particularly preferably 0 to 0.1% or less. The porosity of the second metal film 142 may be calculated by the ratio of the area of the pores in the electrophotographic cross section of the second metal film 142, as with the first metal film 141. The second metal film 142 having a porosity of 0 to 0.5% can be formed by adjusting the temperature and pressure of the compressed gas when forming the second metal film 142 by the cold spray method. The temperature of the compressed gas when laminating the second metal film 142 is preferably 600 ° C. to 1000 ° C. when the first metal film 141 and the second metal film 142 are formed of copper powder, for example, 700 C. to 900.degree. C. is particularly preferred. Further, the pressure of the compressed gas when the second metal film 142 is laminated is, for example, 2.5 MPa to 3.5 MPa when the first metal film 141 and the second metal film 142 are formed of copper powder. Is preferred. By setting the temperature and pressure of the compressed gas within the above ranges, the porosity can be set to 0 to 0.5%, and the second metal film 142 exhibits the same thermal conductivity as that of the bulk metal and has a heat dissipation property. Can be improved.

According to the second embodiment described above, the thermal stress generated by the difference in thermal expansion coefficient between the ceramic substrate, the metal circuit layer, and the cooling fin is improved while improving the adhesion between the ceramic substrate, the metal circuit layer, and the cooling fin. Can be mitigated by the first metal circuit layer and the first metal film having pores at a predetermined ratio, so that cracking of the ceramic substrate can be prevented even under a thermal cycle. In the second embodiment, since the surface roughness of the second metal circuit layer on which the semiconductor chip is mounted is small, there is an effect that the solder wettability is good and the occurrence of mounting defects and the like can be suppressed.

In the second embodiment, the metal circuit layer includes two metal circuit layers (first metal circuit layer and second metal circuit layer), and the cooling fin includes two metal film layers (first metal film and second metal film). Although the power module to be formed has been described, the cooling fin may be formed from one metal film, and the metal circuit layer may be formed from two metal circuit layers (a first metal circuit layer and a second metal circuit layer), Alternatively, even when the metal circuit layer is formed from one metal circuit layer and the cooling fin is formed from two metal films (the first metal film and the second metal film), the same effect is obtained.

A laminate test piece in which a first coating and a second coating made of copper (Cu) are formed on an alumina-based ceramic substrate by the method for manufacturing a laminate according to the present embodiment is manufactured. Evaluation was made on adhesion to the film, heat resistance, and solder wettability.

Example 1
In Example 1, an intermediate layer was formed by applying a brazing material on an alumina base material and then holding it in the atmosphere at 970 ° C. for 1 hour. The intermediate layer is made of silver for the first intermediate layer and titanium hydride for the second intermediate layer, and has a thickness of 30 μm at the thinnest portion and 100 μm at the thickest portion. A metal circuit layer was formed of copper powder on the surface of the first intermediate layer by a cold spray method. The copper powder used has an average particle size of 25 μm and is produced by a water atomization method. In Example 1, the first metal circuit layer uses nitrogen gas (N ₂ ) as a compressed gas, the gas temperature is 400 ° C., the injection pressure is 2 MPa, the thickness is 800 μm, and the porosity is 14%. is there. The second metal circuit layer uses nitrogen gas (N ₂ ) as a compressed gas, the gas temperature is 800 ° C., the injection pressure is 3 MPa, the thickness is 200 μm, and the porosity is 0.1% or less.

(Comparative Example 1)
As Comparative Example 1, an intermediate layer was formed in the same manner as in Example 1, and then a metal circuit layer was formed of copper powder on the surface of the first intermediate layer by a cold spray method. The copper powder used has an average particle size of 25 μm and is produced by a water atomization method. In Comparative Example 1, in order to form a first metal circuit layer (porosity 19%) having a higher porosity than that of Example 1 as the first metal circuit layer, nitrogen gas (N ₂ ) was used as a compressed gas. The gas temperature was 400 ° C., the injection pressure was 2 MPa, and the film was laminated to a thickness of 800 μm. However, the adhesion with the alumina base material was low, and peeling occurred.

(Comparative Example 2)
As Comparative Example 2, an intermediate layer was formed in the same manner as in Example 1, and then a metal circuit layer was formed of copper powder on the surface of the first intermediate layer by a cold spray method. The copper powder used has an average particle size of 25 μm and is produced by a water atomization method. In Comparative Example 2, the first metal circuit layer uses nitrogen gas (N ₂ ) as a compressed gas, the gas temperature is 400 ° C., the injection pressure is 3 MPa, the thickness is 800 μm, and the porosity is 0.5. %. The second metal circuit layer uses nitrogen gas (N ₂ ) as a compressed gas, the gas temperature is 800 ° C., the injection pressure is 3 MPa, the thickness is 200 μm, and the porosity is 0.1% or less.

(Comparative Example 3)
As Comparative Example 3, an intermediate layer was formed in the same manner as in Example 1, and then a metal circuit layer was formed of copper powder on the surface of the first intermediate layer by a cold spray method. The copper powder used has an average particle size of 25 μm and is produced by a water atomization method. In Comparative Example 3, the first metal circuit layer uses nitrogen gas (N ₂ ) as a compressed gas, the gas temperature is 800 ° C., the injection pressure is 3 MPa, the thickness is 800 μm, and the porosity is 0.1. % Or less. The second metal circuit layer uses nitrogen gas (N ₂ ) as a compressed gas, the gas temperature is 400 ° C., the injection pressure is 1 MPa, the thickness is 200 μm, and the porosity is 14%.

(Comparative Example 4)
As Comparative Example 4, an intermediate layer was formed in the same manner as in Example 1, and then a metal circuit layer was formed of copper powder on the surface of the first intermediate layer by a cold spray method. The copper powder used has an average particle size of 25 μm and is produced by a water atomization method. In Comparative Example 4, only one metal circuit layer was formed. The metal circuit layer of Comparative Example 4 uses nitrogen gas (N ₂ ) as a compressed gas, the gas temperature is 800 ° C., the injection pressure is 3 MPa, the thickness is 1000 μm, and the porosity is 0.1% or less.

For the laminates of Example 1 and Comparative Examples 1 to 4, the adhesion between the alumina base material and the first metal circuit layer after the construction of the first metal circuit layer, the first metal circuit layer after the construction of the second metal circuit layer The laminate after forming the metal circuit layer was held at 300 ° C. for 5 minutes, and the laminate was allowed to cool to room temperature, and further at 300 ° C. for 5 minutes. A heat resistance test was carried out for a minute amount, and the crack of the alumina base material was evaluated.

Table 1 shows the structures of the laminates of Example 1 and Comparative Examples 1 to 4, the adhesion of the metal film, and the evaluation results of the heat resistance test. In addition, about Example 1 and Comparative Example 3, while measuring the arithmetic mean roughness (Ra) of the surface of a 2nd metal circuit layer, the cross section of the laminated body after a heat test was observed with the electrophotography. 7 is an electrophotography (40 times) showing a cross section of the laminate according to Example 1 of the present invention, and FIG. 8 is an electrophotography (40 times) showing a cross section of the laminate according to Comparative Example 3. .

In the laminate of Example 1 in which the first metal circuit layer having a porosity of 14% and the second metal circuit layer having a porosity of 0.1% or less were formed, peeling of the circuit layer was observed after each circuit layer was applied. As shown in FIG. 7, the alumina base material did not crack after the heat resistance test. The laminated body of Comparative Example 2 differs from the laminated body of Example 1 only in the porosity of the first metal circuit layer, but the porosity of the first metal circuit layer is as small as 0.5%. The relaxation was not sufficient and cracks occurred in the alumina substrate. Similarly, in Comparative Example 4 which does not have a metal circuit layer with a porosity of 5 to 15%, which can relieve thermal stress, cracks occurred in the alumina base material in the heat resistance test. The laminate of Comparative Example 3 includes the first metal circuit layer having a porosity of 0.1% or less and the second metal circuit layer having a porosity of 14%. The first metal circuit layer has a porosity of Therefore, the thermal stress was not sufficiently relaxed by the heat resistance test, and the alumina base material was cracked (see FIG. 8).

On the other hand, the arithmetic mean roughness of the surface of the second metal circuit layer of Example 1 was 8.4 μm, and it was confirmed that the solder wettability was good, but the surface of the second metal circuit layer of Comparative Example 3 was good. It was confirmed that the arithmetic average roughness of was as very large as 12.2 μm. The arithmetic mean roughness of the first metal circuit layer of Example 1 is 11.9 μm, and when only the first metal circuit layer having a porosity of 5 to 15% is formed on the metal circuit layer, the thermal stress is increased. Although it can be mitigated, cracking of the ceramic substrate can be prevented, but poor solder wettability tends to cause mounting defects.

As described above, the laminate, the insulating cooling plate, the power module, and the method for producing the laminate according to the present invention are useful when joining a ceramic substrate and a metal film, and are particularly inferior in heat resistance. Is suitable for use as a ceramic substrate.

1

Electronic circuit board

10, 110

Ceramic substrate

20, 120

Metal circuit layer

21, 121 First

metal circuit layer

22, 122 Second

metal circuit layer

30, 130

Semiconductor chip

50, 150

Intermediate layer

51, 151 First

intermediate layer

52 , 152 Second intermediate layer 60 Cold spray device 61 Gas heater 62 Powder supply device 63 Gas nozzle 64 Spray gun 100 Power module 140 Cooling fin 141 First metal coating 142 Second metal coating

Claims

An insulating ceramic substrate;
An intermediate layer mainly composed of a metal or an alloy formed on the surface of the ceramic substrate;
A first metal film having a porosity of 5 to 15%, which is formed by accelerating a powder containing a metal together with a gas on the surface of the intermediate layer and spraying and depositing the powder in a solid state on the surface; ,
Formed by accelerating together with gas a powder containing the same metal as that forming the first metal film on the surface of the first metal film, and spraying and depositing the powder in the solid state on the surface. A second metal film having a porosity of 0 to 0.5%;
A laminate comprising:
The intermediate layer is
A first intermediate layer comprising a metal or an alloy as a main component and forming a layer on the first metal film side;
The active metal, or an active metal oxide or hydride, is in contact with the first intermediate layer, and is bonded and laminated to the ceramic substrate on a surface different from the surface in contact with the first intermediate layer. 2 intermediate layers,
2. The laminate according to claim 1, wherein the first intermediate layer and the second intermediate layer are formed by applying a brazing material to the ceramic base material and then performing a heat treatment.
The laminate according to claim 2, wherein the intermediate layer is formed by heat treatment in a vacuum.
4. The laminate according to claim 3, wherein the second intermediate layer includes at least one selected from the group consisting of a metal selected from titanium, zirconium, hafnium, germanium, or a metal hydride.
The laminate according to claim 3 or 4, wherein the first intermediate layer includes at least one selected from the group consisting of gold, silver, copper, aluminum, and nickel.
The laminate according to claim 2, wherein the intermediate layer is formed by heat treatment in the atmosphere.
The second intermediate layer includes at least one selected from the group consisting of titanium, zirconium, hafnium, germanium, boron, silicon, aluminum, chromium, indium, or a metal oxide or hydride. Item 7. The laminate according to Item 6.
The laminate according to claim 6 or 7, wherein the first intermediate layer contains at least one of gold and silver.
The laminate according to any one of claims 1 to 8, wherein the first metal film and the second metal film are made of copper, aluminum, or an alloy of these metals.
The laminate according to any one of claims 1 to 9, wherein the ceramic substrate is alumina.
An insulating cooling plate comprising the laminate according to any one of claims 1 to 10,
The ceramic substrate has a heat dissipation part,
The insulating cooling plate, wherein the first metal film and the second metal film are circuit layers.
A power module comprising the laminate according to any one of claims 1 to 10,
The ceramic substrate is an insulating substrate;
The first metal film and the second metal film are circuit layers;
A power module, wherein a cooling plate mainly composed of copper or aluminum is formed on a surface of the insulating substrate different from the surface on which the first metal film and the second metal film are formed.
A method for producing a laminate in which a metal film is formed on the surface of a ceramic substrate,
An intermediate layer forming step of forming an intermediate layer mainly composed of a metal or an alloy on the surface of the ceramic substrate;
A powder containing metal is accelerated on the surface of the first intermediate layer formed by the intermediate layer forming step together with a gas, and sprayed and deposited in a solid state on the surface to have a porosity of 5 to A first metal film forming step for forming a 15% first metal film;
By accelerating a powder containing the same metal as the metal forming the first metal film together with a gas on the surface of the first metal film and spraying and depositing the powder in the solid state on the surface, the porosity is increased. A second metal film forming step of forming a second metal film of 0 to 0.5%;
The manufacturing method of the laminated body characterized by including.
The intermediate layer forming step includes
A brazing material disposing step of disposing a brazing material on the surface of the ceramic substrate;
By heat-treating the ceramic base material on which the brazing material is disposed in the brazing material disposing step, the first intermediate layer and the first intermediate layer are in contact with the first intermediate layer and the surface in contact with the first intermediate layer. A heat treatment step of forming an intermediate layer having a second intermediate layer that is bonded and laminated with the ceramic base material in a different plane;
The manufacturing method of the laminated body of Claim 13 characterized by the above-mentioned.